M. StifFt 071 the Origin of Mineral Springs. 295 



sequence of this solution, these different rocks would undergo 

 an inevitable change of composition. Where, however, I may 

 ask the geognost, do we find these changed basalts, clinkstones, 

 and greenstones? A clinkstone or a basalt which has been 

 deprived of its carljonate of soda, is no longer either a clink- 

 stone or basalt. "We certainly observe that almost all mi- 

 neral waters exert a sort of action on the surrounding rocks, con- 

 verting them into an earthy sort of mass ; but these effects are 

 limited to the immediate vicinity of the springs, and consequent- 

 ly cannot be taken into account in the present instance. These 

 changes seem, moreover, to consist rather in a diminution in the 

 cohesion of the parts of the rock, than in their chemical decom- 

 position. Hot springs generally burst out in the lowest situa- 

 tions, and are more abundant both in water and in foreign 

 contents, but contain less gas, especially less carbonic acid, than 

 cold springs which emerge at a greater elevation. This rule 

 holds true both of the hot springs of Nassau and Bohemia. 

 Now, this is directly the reverse of what we ought to expect, ac- 

 cording to the theory of solution ; for the carbonic acid ought 

 to promote the solvent power of the water on the rock. Cold 

 springs, which contain a larger dose of this acid, ought to attack 

 the rock with greater force, and the more as, on account of their 

 greater elevation, they are longer in contact with it, and contain 

 more solid matters, which is the contrary of what actually occurs. 

 Recent researches have detected many ingredients in mineral 

 waters, which were in vain sought for by the older analysts. 

 This seems to me to be also at variance with the theory of so- 

 lution, which might explain the want of an ingredient former- 

 ly known to exist ; but not the occurrence of a new substance, 

 especially when of easy solubility, as the carbonate of soda^ 

 which has been lately found in the Pyrmont water. The great 

 quantity of carbonic acid which rises from the interior of the 

 earth, has been explained upon the supposition of the existence 

 of great deposits of carbonate of soda in the focus of volcanic 

 activity. Is it not, then, much more reasonable to suppose that 

 this alkaline salt found in mineral waters, ascends from this fo- 

 cus, tliau that it was lixiviated from the solid rock ? The for- 

 mer is certainly the more credible, when we know that carbonate 

 of soda is sublimed during volcanic eruptions. 



